The present invention is directed generally to electronic data transfer, and more particularly, to current modulation-based communication from a slave device, such as for use in an electronic blasting system.
In the prior art electronic blasting systems, communication from slave detonators back to a blasting machine has been effected by voltage modulation from the detonator. The disadvantages associated with this include the necessity of having sufficient power in the detonator to drive the modulated voltages back to the blasting machine (resulting in increased power consumption and circuit complexity), and possible interference from environmental factors such as EMI, ESD, RFI, which may impair proper data transmission.
While current modulation-based “talkback” from a slave device to a master device has been employed in other fields (e.g., RS-485), this has typically been done with the master device holding the bus voltage high. In electronic blasting systems (and other applications), however, the background current draw is generally relatively noisy when the bus voltage is high, because at that time the detonators may be performing tasks such as active charging, charge-topping of firing capacitors, irregular current consumption of each detonator via charging of buffer capacitors, etc. Such background noise thus interferes with the successful and accurate reception of data by the master device. Presumably for these reasons it has heretofore not been thought possible or useful to employ current modulation-based talkback in an electronic detonator system.